Generally, a washing machine can be classified into a pulsator type washing machine having a drum standing in a vertical direction, and a drum type washing machine having a drum lying in a horizontal direction.
Since the drum type washing machine lies in the horizontal direction, it performs washing operation in such a way of lifting and then dropping laundry within the drum.
FIGS. 1 and 2 schematically show a conventional drum type washing machine operated as mentioned above.
The drum type washing machine comprises a body 10, an outer tub 20 installed within the body 10, a drum 30 rotatably installed in the outer tub 20, a water supply pipe 50 to guide flow of water, and a driving unit to drive the drum 30.
Here, the body 10 is provided at a front side thereof with an input port 11 through which laundry is input to the body 10, and a door 40 attached to the input port 11 to open and close the input port 11.
The outer tub 20 has a damper 21, which is provided at either lower side around an outer periphery while being supported on an inner surface of the body 10.
The outer tub 20 is provided therein with a heater 80 on a bottom surface thereof to control the temperature of water used for washing the laundry.
The drum 30 is rotatably installed within the outer tub 20, and has a plurality of apertures 31 formed around an outer peripheral surface thereof such that water flows into and from the drum 30 therethrough.
The water supply pipe 50 is a passage through which the water for washing the laundry flows within the washing machine, and serves to guide the water supplied from a water pipe through a water supply valve 51 into the outer tub 20.
Meanwhile, the washing machine further comprises a detergent storage part 52 at the passage of the water supply pipe 50 to store detergent required for washing operation such that the detergent is added to the water supplied into the outer tub 20.
The detergent storage part 52 is provided in an upper space inside the body 10, and is adapted to allow input of detergent.
In addition, a distal end of the water supply pipe 50 is connected with an upper end of the outer tub 20 at a front side thereof such that water gradually fills up the outer tub 20 and the drum 30 from the bottom surface thereof after natural fall of the water.
The driving unit comprises a driving motor 71 to drive the drum 30, and a belt 72 connected between the driving motor 71 and the drum 30 to transmit driving force of the driving motor 71 to the drum 30.
However, the conventional drum type washing machine as described above provides simple functions of washing and drying the laundry, and does not provide other functions.
Furthermore, even for a small amount of laundry or laundry with small amount of contaminants, the conventional drum type washing machine requires not only a great amount of water, but also substantially the same period of time as that for a general washing operation, causing unnecessary consumption of electricity.
Recently, it is needed to provide a washing machine having an improved structure, which enables washing operation to be performed as efficiently as possible using as little water as possible.
Furthermore, although a controller of the washing machine serves to control the heater installed in the tub to warm the water, it does not serve to control the heater to generate steam. As a result, the conventional drum type washing machine cannot provide effect of washing the laundry with the steam. One of methods for enhancing washing effect is to increase the temperature of surroundings of the laundry. However, even with this method, it is insufficient to enhance the washing effect only with the water warmed in the tub.